Hydrofluorocarbon (HFC) refrigerants have become widely used in refrigeration and air-conditioning apparatus throughout the world. HFCs became the refrigerant of choice as first chlorofluorocarbons and now hydrochlorofluorocarbons have been phased out due to their deleterious effect on the ozone layer. HFC refrigerants were developed as intermediate replacements, but some have been identified as having high global warming potential (GWP). New regulations relating to GWP are being adopted thereby requiring the industry to move to alternative refrigerants having an acceptable GWP.
Several types of molecules have been in use or proposed for use in place of the high GWP refrigerants. Many low GWP alternative refrigerants have issues related to toxicity or flammability. The industry has avoided the use of flammable refrigerants in many regions in the world due to the safety factor particularly with respect to consumer products used in homes and automobiles.
It is the object of the present invention to identify means by which flammable refrigerants could be used as replacements for the higher global warming refrigerants currently in use. If currently available flammable refrigerants are used in place of existing refrigerants, the cost of this conversion can be minimized and the ultimate savings will be to the consumer.
Many of the refrigerant blends being sold to replace CFCs or HCFCs have been formulated such that they are non-flammable. But it is often the non-flammable component of the blend that contributes most to the blend's GWP. The higher number of fluorine atoms on the molecule reduces the flammability, but also increases the GWP. The more flammable HFCs have a lower number of fluorines (and thus lower GWP), but the corresponding increase in the number of hydrogens yields a flammable compound.
The art discloses many compositions as having particular utility in the refrigeration and air-conditioning industry due to their non-flammable nature. Many of these compositions are made non-flammable by way of dilution of the flammable component with a known non-flammable refrigerant.
The present invention addresses flammability of the entire refrigerant composition. Often times, the lubricant, which is necessary in most vapor compression refrigeration or air-conditioning systems, is combustible. The present invention addresses this issue by providing compositions that have reduced overall flammability when considering both the refrigerant and the refrigerant/lubricant compositions as compared to those compositions available at present.